In beverages such as coffee, tea and cocoa being served by a dispenser for beverage, a dairy product such as an emulsified liquid composition is used as a whitener, or as a milk component of cafe au lait or cocoa. Such a dairy product is stored separately from components such as a stock solution of coffee, tea and cocoa and a sugar stock solution within a dispenser. Immediately before drinking, the dairy product is at first ejected through a nozzle so as to dilute it with cold water or warm water, and then served to a drinking cup together with a component such as coffee or a sugar component being dispensed separately, or directly served into the drinking cup, and then diluted and mixed with a main component such as coffee in the cup.
In order to serve a beverage having a certain flavor, operations such as ejection, dilution and dispensation, or operations of ejection and dispensation in the dispenser are required to be accurate. When a stock solution in the dispenser has high viscosity and the stock solution itself causes component separation, a certain constant dispersing volume cannot be attained. Furthermore, a beverage containing contents with separation or solidification, gives consumers concern about perishability and unpleasantness. Therefore, it is necessary that a dairy product such as an emulsified liquid composition has a property of giving a preferable taste upon ejection from an inside of a dispenser to beverages such as coffee, tea and cocoa through a proper concentration and components. Moreover, it is also necessary that a dairy product has proper low level of viscosity so as to maintain a stable amount of the dairy product to be ejected from the dispenser.
On the other hand, in view of storage stability, a dairy product is preferably a product which maintains stable quality until it is supplied to the dispenser even when stored for a long period. An emulsified liquid composition currently used is mainly an oil-in-water type emulsion, and is usually prepared by mixing a milk fat, a milk protein or a component analogous thereto, an emulsifier and a flavor, followed by homogenization. However, these components may be easily solidified during storage, or may cause separation of the fat or protein when being used after storage.
In order to distribute a dairy product or a whitener used as a milk component for coffee, tea and cocoa, at an ambient temperature, it is necessary to be formed into such as evaporated milk or condensed milk having high concentration of constituent components and to control microorganisms thoroughly such as by heat sterilization, utilization of principle of sugar preservation or a use of an impermeable sealed container. However, in the evaporated milk or condensed milk obtained by subjecting to a heat treatment or increasing a sugar content, heat deterioration may occur depending on the conditions, and sweetness generates as a result of adding sugar, and thus quality and flavor may vary and also viscosity increases. For example, when retort heating is carried out at a high temperature of 115° C. for about 15 to 20 minutes, heat deterioration is caused by an aminocarbonyl reaction between the sugar and the milk component, and by an influence of the residual oxygen immediately after a sterile production. Furthermore, after storage at an ambient temperature, browning reaction proceeds and also flavor deteriorates. Such a composition having high viscosity is not suited for use in a conventional dispenser since it is very difficult or impossible to eject the composition from the inside of the dispenser when used in the dispenser.
Storage at low temperature is useful means for storage for a long period. Particularly, when heat sterilization and principle of sugar preservation cannot be utilized, cryopreservation is a useful means, which enables storage for a longer period, as compared with chilled storage. However, problems of solidification of the emulsified liquid composition composed mainly of milk during storage, and separation of the fat or protein caused by the use after storage become more markedly during the process of freezing and the following thawing. Namely, an emulsified state, which was uniform at an initial stage, is deteriorated by freezing and, when thawed and diluted, the state turns into a non-uniform state or separation of the milk component arises. In addition, since chilled storage is carried out at a low temperature of 2 to 6° C. for a certain period of time in the dispenser at any rate, viscosity may tend to increase in the mean time.
Japanese Unexamined Patent Publication No. 2001-69910 discloses, as a method for improving quality stability after freezing and thawing of a coffee whitener, a method of adding to an oil phase as an emulsifier, a polyglycerin fatty acid ester, which contains behenic acid as a main constituent fatty acid and has an esterification degree of 50% or more.    Patent Document 1: Japanese Unexamined Patent Publication No. 2001-69910